Bù hǎoyìsi, chā yí jù.
Sorry, let me jump in with one line.
The standard polite cut in. Promising it is just one sentence buys you the floor, so keep the promise.
REAL SPOKEN CHINESE
Apologise first, then cut in. The polite pattern in Chinese is a small opener like sorry to jump in or let me say one thing, then your point, and the opener is what makes the interruption acceptable in a meeting or with elders. Without the opener, the same words land as rudeness.
Bù hǎoyìsi, chā yí jù.
Sorry, let me jump in with one line.
The standard polite cut in. Promising it is just one sentence buys you the floor, so keep the promise.
Dǎrǎo yíxià, wǒ wèn ge shì.
Sorry to disturb, quick question.
For breaking into someone's work or a stranger's conversation. Darao frames the interruption itself as the thing you are sorry for.
Wǒ xiān shuō yí jù.
Let me say one thing first.
Firm but still polite, for meetings where the talk is drifting. The xian claims the floor for one sentence, not forever.
Děngdeng, gāngcái nàge méi tīng dǒng.
Wait, I did not get that last part.
Interrupting to ask for a repeat is always allowed, because it flatters the speaker: you were actually listening.
Nǐ gāng shuō shénme láizhe?
What were you just saying?
The laizhe does the softening. Without it the same question sounds like a challenge, with it you are just backtracking.
Néng ràng wǒ shuōwán ma?
Can I finish my sentence?
For when you are the one being interrupted. Phrasing it as a question keeps it civil, phrasing it flatter would start a row.
Tíng, wǒ jiē ge diànhuà.
Hold on, I have to take this call.
The phone trumps the conversation and nobody minds. The ting is a handbrake, fine with peers, too abrupt for your boss.
Bié shuō le, tīng wǒ de.
Stop talking, listen to me.
A hard cut in between close friends, usually mid argument. To anyone outside that circle it is pure disrespect.